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Curtain Walls vs Window Walls: Key Differences

In commercial construction, glass is a versatile design element. It can serve decorative and functional purposes, and glass exterior facades are one of the most popular elements in modern mid- and high-rise design. Builders have numerous options for integrating glass into exterior walls, but two of the most common are curtain walls and window walls.

Although both types of systems deliver a similar look, they’re installed and built in much different ways. Curtain walls, for example, are large metal-framed sheets of glazing that are anchored from the floor slabs of a building. In effect, curtain walls – which are non-load bearing – hang like curtains from the structure.

Window walls, alternatively, are mounted in between the concrete floor slabs. These panels– which are typically pre-manufactured, are sealed with caulking and tape, and like curtain walls, they are non-load bearing.

Curtain Walls: Installation Specifics and Benefits

There are numerous types of curtain wall systems, and they’re differentiated by how the system is constructed. Typically, a curtain wall system integrates different sized mullions – which are metal poles that make up the framing of the panels. Glazing can then be attached to the mullions onsite, but there are also prefabricated panel systems that can be anchored to the slabs. The most common types of curtain wall systems include:

•Stick System: Stick curtain walls require vertical mullions to be installed and anchored to the floor slabs. Typically they are glazed in the field, and additional components like horizontal mullions and spandrel panels are attached once the vertical mullions have been set.

•Panel System: Panel curtain walls are less cost-intensive than stick systems. Essentially, large panels are pre-fabricated off-site and then attached to anchors within the building structure.

•Unit-and-mullion system: A hybrid system, this type of curtain wall requires mullions to be anchored to the structure, and then pre-fabricated units are attached to the mullions.

•Column-cover-and-spandrel: Similar to the stick system, this type of curtain wall utilizes large cladding components (column and spandrel covers), which serve as sticks.

Window Walls: Installation Specifics and Benefits

Window walls offer a cost-effective alternative to curtain walls while achieving a similar look for the building’s exterior. Traditionally, window wall units are manufactured and glazed off-site. This eliminates the need for time-intensive construction of the mullion system and on-site glazing, which is common for curtain walls.

The greatest advantage of window walls is the cost savings. Many window wall systems can cost half or in some cases one-third of the cost of curtain walls. Since window walls are compartmentalized between floors, the risk of sound transmittance is greatly reduced, as noise cannot reverberate across the entire system. Window wall products are also typically pre-tested and pre-certified by the manufacturer, which can also help to reduce costs, and they can reduce project cycle times due to the optimized installation.